Double Volute Casing Drain Hole [API610]

[GaTechTheron]

I have a somewhat large API610 OH2 pump with a double volute. This pump is holding crude in the "inner" volute because it does not get a chance to drain. The hole drilled through this "inner" volute (connecting the two volutes for drainage purposes) is drilled at 1/8" and keeps clogging. Does anyone know if API specifies what size this hole should be? 1/8" seems somewhat small. I hope this was clear. Thanks for your help!

 

[JJPellin]

You did not mention what size the pump is. But, based on the comparable pumps that I have overhauled, I would expect this hole to be at least 1/4" or 3/8". You are correct. A 1/8" hole is too small (especially for crude service).

Johnny Pellin

 

[GPRnD]

API 610 does not specifiy the size of drain holes. It only asks for the pump to be as self draining as is practical.

The general use of 1/8" is because elsewhere in API 610, size of orifices is limited to 1/8" or larger.

A 1/4" or larger hole will have no effect on the performance unless you get too ambitious with your drill.